For transmission of video signals, a format of non-compressed video signals developed by the Society of Motion Picture and Television Engineers (SMPTE) 125M standard. FIG. 5 illustrates a 525/60 TV video signal, in which auxiliary data areas H, D, and V are capable of being multiplexed with auxiliary data. A full line period, except switching points, of video samples 1444 to 1711 is assigned as the auxiliary data area H. A period of video samples 0 to 1439 at lines after effective video area and before the switching point is assigned as the auxiliary data area V. And at lines after the switching point to succeeding effective video area is assigned as the auxiliary data area D.
A format of an auxiliary data packet to be multiplexed in the auxiliary data areas is shown in the SMPTE 291M standard. FIG. 6 illustrates the format of the auxiliary data packet of the SMPTE 291M standard where one word consists of 10 bits. As shown in FIG. 6, the auxiliary data packet includes three words (000h, 3FFh, and 3FFh) of an auxiliary data flag (ADF), one word of a data identification (DID), one word of second data identification (SDID), one word of a data count (DC), 0 to 255 words of a user data word (UDW), and one word of a check sum (CS).
Another format of a compressed video signal is shown in the SMPTE 314M standard. FIG. 7 illustrates a data structure of a 50M mode compressed video signal of the SMPTE 314M standard where hatching areas represents areas capable of being multiplexed with data. In either a digital interface (DIF) block data area in a video auxiliary (VAUX) section or a reserve data are in a video section, the data can be multiplexed. One word consists of 8 bits.
As the location where the auxiliary data packets are multiplexed in a non-compressed video signal is not particularly specified, the auxiliary data packets are hardly restored at their original location during the conversion of the compressed video signal into its non-compressed signal.